The former puppeteer for Sesame Street's Elmo faces a new accusation of having sex with an underage boy, a week after a similar allegation prompted him to resign from the iconic children's programme.

In a lawsuit filed in the US District Court in Manhattan, a man identified only as John alleges Kevin Clash engaged in sex acts with him when he was 16 years old. The suit seeks at least US$75,000 ($91,497) in damages.

The suit alleges the incident occurred in either 2000 or 2001 when John, who is from Florida, visited New York for modelling opportunities.

John came to know Clash, then 40, through a gay telephone chat line on which Clash claimed to be a 30-year-old named Craig, according to the suit.

John returned to New York when he turned 18, and he and Clash renewed the relationship, the lawsuit said.

"Mr Clash believes the lawsuit has no merit," Clash's publicist said in an emailed statement.

It is the latest charge levied against Clash, now 52, who resigned on November 20 from Sesame Workshop, the company behind Sesame Street, after nearly 30 years on the show.

His resignation came the same day Cecil Singleton filed a claim seeking more than US$5 million in damages from Clash. Singleton claims he met the then-32-year-old puppeteer in 1993 in a gay chat room when he was 15.

It added that on numerous occasions over a period of years Clash engaged in sexual activity with Singleton.

The newest allegation comes about two weeks after another man recanted his claims that Clash had sex with him when he was 16-years-old. The man later said the relationship was consensual.

Clash had denied the allegations and acknowledged a past relationship with his first accuser. He added the pair were both consenting adults at the time.

The Elmo character debuted on Sesame Street in 1979, 10 years after the show premiered and introduced the now-iconic characters Big Bird, Bert and Ernie, Oscar the Grouch and Cookie Monster, among others, to American children.

While Clash was the third performer to animate the child-like shaggy red monster, Sesame Workshop credits him with turning Elmo into the international sensation he became.